Agglomerating nozzle



AGGLOMERATING NOZZLE Filed Dec. 6, 1967 2 Sheets-Sheet 1 Oct. 6, 1970 e. GENTON ETAL AGGLOMERATING NOZZLE Filed Dec. 6. 19s? 2 Sheets-Sheet 2 w/fl/ZWZ \m x w United States Patent US. Cl. 99-234 2 Claims ABSTRACT OF THE DISCLOSURE Apparatus for agglomerating powdered materials, especially powdered food products, comprises a nozzle for injecting the powder into an enclosure and nozzles arranged inside and outside the jet of material to inject fluid, preferably steam, into the material as it is ejected from the nozzle.

The invention relates to an apparatus for agglomerating pulverulent products and also the products obtained using this apparatus.

It is known to agglomerate pulverulent products, especially food products, in order to improve their miscibility. The process most commonly employed consists of humidifying the particles of the pulverulent product so that the particles tend to stick to each other and form agglomerates.

Various installations are used for this purpose. They most frequently comprise an enclosure of generally cylindrical form, known as an agglomerating tower, equipped with devices for projecting jets of fluid on the inside. The pulverulent product is introduced at the top, is humidified while passing the fluid jets, agglomerates while descending the tower and leaves the bottom in agglomerated condition. At intervals, the agglomerates are dried by means of a current of hot air passing through the tower from the bottom to the top and finally by a drying device placed at the end.

The jets of fluid, generally saturated steam, sometimes mixed with water, are projected inside the tower by means of a series of radial nozzle or pierced tubes, the latter generally arranged in pairs, the holes are approximately facing each other. These devices for projecting the steam are satisfactory to some extent, but their performance is no more than moderate: to obtain the humidification necessary to agglomerate the particles the production is relatively limited.

In order to increase the production, it has been suggested, instead of projecting the steam in a direction more or less perpendicular to the trajectory of the particles, to project it parallel to the trajectory by means of a tube concentric with the path of the particles, either inside or outside the path, the latter arrangement being preferred. Using such an apparatus, the production can be increased to an important extent for the same size of tower. This increase is however limited by factors inherent in the principle of the apparatus. In effect, the introduction of steam concentrically with the pulverulent material to be agglomerated itself produces a suction effect. As this effect increases very fast with increasing velocity of the steam, an increase in this velocity increases the flow of pulverulent material to the point at which the particles are not sufficiently humidified. Also, as the diameter of the path of flow of the pulverulent material is increased, the centre of the stream of pulverulent material tends to be less humidified than the periphery. As is well known, it is possible to increase the input of steam to compensate, but it is clear that this is less economic. Moreover, if it is necessary to excessively humidity the particles at the periphery to give adequate humidification at the centre the drying is made more difiicult. The multiplication of nozzles for the pulverulent material in the same tower, which can also be envisaged for increasing the production, is a more rational solution the input of drying air and the size of the tower being in all respects proportional to the input of pulverulent material. However, the equal division of the total input between the different nozzles poses difficult problems.

The apparatus according to the invention avoids the disadvantages of known apparatus in that it allows a considerable increase in the production of agglomerates for the same size of tower and for the Same input of steam. Also the product obtained is distinguished by a greater homogeneity and the proportion of fines is reduced.

According to the invention, a method of agglomerating a pulverulent material comprises projecting a jet of the material into an enclosure, projecting at least one jet of fluid into the enclosure to impinge on the outside of the jet of material and projecting another jet of fluid to impinge on the inside of the jet of material.

Also according to the invention, an apparatus for agglomerating a pulverulent material comprises at least one tubular nozzle for projecting the pulverulent material into the enclosure, at least one outer nozzle for projecting the fluid outside the jet of pulverulent material and at least one inner nozzle for projecting the fluid inside the jet of material. In a preferred embodiment, the inner nozzle comprises an annular orifice.

The accompanying drawing shows, by way of example only, a preferred embodiment of the apparatus of the invention.

FIG. 1 shows schematically, in longitudinal section, an agglomerating installation equipped with an apparatus according to the invention.

FIG. 2 represents, on a larger scale and in partial longitudinal section, the apparatus according to the invention.

In the installation shown in FIG. 1, the casing of an agglomerating tower, of known type, is shown by 1. A conduit 2 leads in the drying air, which is led out through conduit 3 to a cyclone separator 4 for recovering the fines. The interior of the casing is preferably maintained at low pressure.

A conduit 5 leads the pulverulent material to be agglomerated to the agglomerating device 6 Which is fed with saturated steam by conduit 7. Alternatively, the device 6 can be supplied with a mixture of water and steam.

The agglomerating device 6, one of the objects of the invention, is represented in greater detail in FIG. 2. It comprises essentially:

A tubular nozzle 9 for directing the pulverulent product to be agglomerated, supplied by conduit 5, an outer nozzle 10 for projecting the vapour, concentric with the element 9, and an inner nozzle 11 for projecting the vapour.

In the form of execution shown, the tubular nozzle 9 has an unobstructed circular section. Experience has shown that accidental obstructions, unfortunately common in known devices, are generally caused by the presence of valves, grills, intersections and other obstacles in the tubular nozzle.

The tubular nozzle 9 is slightly widened at its end. The outer nozzle 10 is supplied with steam through conduit 7 from chamber 8: it comprises an exterior lip slightly set back from the mouth of tubular nozzle 9 which is shaped such that the outer nozzle is in the form of a section of an annular cone.

In the preferred form which is shown in the drawing, the inner nozzle 11 is composed of a tubular element 12 for directing the steam received from conduit 7, this tubular element being covered by a cone 13 carried by a central stem 14 and a supporting member 15 integral with element 12. The lip of element 12 and the edge of cone 13 thus define an orifice of annular shape for projecting the steam. More precisely, the exit of the inner nozzle 11 has the form of an annular ring.

The inner nozzle 11 is arranged downstream of the mouth of tubular nozzle 9. By means of a device not shown, the position of the inner nozzle 11 relative to the mouth of tubular nozzle 9 is adjustable so as to vary the distance between them.

The operation of the apparatus described is as follows: The pulverulent product is directed and ejected by the nozzle 9. It comes into contact with the jet of steam leaving the nozzle 10. There is a certain spreading of the jet of pulverulent product because of the widened form of the mouth of nozzle 9. At the same time the jet of steam concentric with the jet of pulverulent product tends to spread because of the contraction of the exterior edge of the nozzle 10 with respect to its inner edge. This effect is further reinforced by the difference in pressure between the tubular nozzle and the outer nozzle on the one hand and the wall on which they impinge on the other.

The two jets, of pulverulent product and steam, thus together have the form of a cone open at its base. At its edge, the inner nozzle 11 projects a sheet of steam also in the form of a cone, but of wider angle. The product particles farthest towards the interior of the jet leaving the nozzle 9, which do not come into contact with the jet of steam from the nozzle 10, therefore must meet the sheet of steam leaving the nozzle 11. Also the intersection of the two steam cones from nozzles 10 and 11 produces a tubulence which ensures a complete humidification of the product particles. The results of measurements carried out shows that the apparatus according to the invention has the following advantages over hitherto known apparatus:

The consumption of steam, relative to the output of product, is somewhat reduced. The percentage of unusable fines which are recovered by the cyclone and must be recycled and so reduce the efliciency of the installation is reduced in the proportion 5:1. For the same diameter of tubular nozzle, the production is doubled. Control of the texture of the agglomerate is much easier.

EXAMPLE The table below gives the results of sieving two agglomerated powders, one by means of a conventional device, i.e. without an inner nozzle, the other by means of a device according to the invention. Both were obtained from the same mixture of sugar and cocoa. These results are expressed as the percentage by weight rejected by different sieve apertures.

Sieve Corresponding Conven- Inven- Aperture, U.S. Standard tional tion Microns Sieve Nozzle Nozzle 4 mesh against (-95.8):4.2% with the device according to the invention.

The invention can be used for agglomerating many types of product, especially food products such as tea or soluble coffee, whole or skimmed milk powder, foods for babies etc.

We claim:

1. Apparatus for agglomerating pulverulent material comprising in combination a casing enclosing a space constituting an agglomerating zone, and an agglomerating device including a tubular nozzle,

a conduit connected with said tubular nozzle for supplying pulverulent material thereto, said nozzle outletting within the space enclosed by said casing for projecting a jet of the pulverulent material into said agglomerating zone,

another nozzle encircling said tubular nozzle and having communication with a source of pressurized fluid, said other nozzle having outlet therefrom Within said agglomerating zone adjacent the outlet of said tubular nozzle for directing a stream of pressurized fluid into said zone concentrically with the outflow of material from said tubular nozzle, said tubular nozzle having a mouth widening toward its tip end and the outlet of said other nozzle being set back slightly upstream of the outlet of said tubular nozzle whereby a concurrent flow of material from said tubular nozzle and of pressurized fluid from said other nozzle issues therefrom as a cone discharge having an open base end remote from the outlets of said tubular and other nozzles with the pressurized fluid located exterior of said pulverulent material, and

a third nozzle positioned within said casing downstream of the outlets of said tubular nozzle and said other nozzle, said third nozzle comprising a tubular conduit disposed within said casing co-axially with said tubular nozzle and having a tip end, a cone shaped member fixed to the tip end of said tubular conduit, said cone shaped member having its apex proximate and its base end remote from the outlet of said tubular nozzle, the base end of said cone being spaced from the tip end of said tubular conduit whereby the edge of the base end of the cone and the tip end edge of said tubular conduit define an annular orifice for issuing a stream of pressurized fluid therefrom laterally of the axis of said tubular nozzle and said other nozzle, said annular orifice being spaced from the outlets of said tubular nozzle and said other nozzle such that the pressurized fluid issues therefrom internally of the cone of material and pressurized fluid issuing from said tubular and other nozzles.

2. Apparatus for agglomerating pulverulent material comprising in combination a casing enclosing a space constituting an agglomerating zone, and an agglomerating device including a tubular nozzle,

a conduit connected with said tubular nozzle for supplying pulverulent material thereto, said nozzle outletting within the space enclosed by said casing for projecting a jet of the pulverulent material into said agglomerating zone,

another nozzle encircling said tubular nozzle and having communication with a source of pressurized fluid, said other nozzle having outlet therefrom within said agglomerating zone adjacent the outlet of said tubular nozzle for directing a stream of pressurized fluid into said zone concentrically with the outflow of material from said tubular nozzle, whereby a concurrent flow of material from said tubular nozzle and of pressurized fluid from said other nozzle issues therefrom as a cone discharge having an open base end remote from the outlets of said tubular and other nozzles with the pressurized fluid located exterior of said pulverulent material, and

A third nozzle positioned within said casing downstream of the outlets of said tubular nozzle and said other nozzle, said third nozzle comprising a tubular nozzle such that the pressurized fluid issues therefrom internally of the cone of material and pressurized fluid issuing from said tubular and other nozzles.

References Cited conduit disposed within said casing co-axially with 5 said tubular nozzle and having a tip end, a member UNITED STATES PATENTS having a circular edge fixed to the tip end of said 3,085,492 4/1963 99' 234 tubular conduit, said member being spaced from 3143'428 8/1964 Relmers et 99 234 XR the tip end of said tubular conduit whereby the cir- 3,331,306 7/1967 Hutton 99 234 cular edge of the member and the tip end edge of 10 said tubular conduit define an annular orifice for issuing a stream of pressurized fluid therefrom laterally of the axis of said tubular nozzle and said other nozzle, said annular orifice being spaced from 15 the outlets of said tubular nozzle and said other 34*468 FREDERICK L. MATTESON, 111., Primary Examiner H. B. RAMEY, Assistant Examiner US. Cl. X.R. 

